Radio Frequency (RF) communication devices such as receivers and transmitters are sometimes implemented using multi-die packages, which are referred to as Multi-Chip Packages (MCP), Multi-Chip Modules (MCM), Systems-in-Package (SiP) or Systems-on-Chip (SoC). When multiple dies are packaged in a single package, signals emitted from one die may interfere with the operation of another die.
Various techniques have been proposed for reducing inter-die interference. For example, U.S. Patent Application Publication 2008/0237825, whose disclosure is incorporated herein by reference, describes a stacked integrated circuit package that includes a first device and a second device. A conductive spacer structure, having a spacer filler around a conductive element, is formed over the first device. The second device is mounted over the conductive spacer structure. The first device, the second device, and the conductive spacer structure are encapsulated.